When did the patent application number begin to use 12 digits?

The current patent number in China is represented by 12 Arabic numeral plus check digit, including application year number, application category number and application serial number. This has been implemented since 2004. Before 2003, it was all nine digits. (8 digits plus a decimal point)

These include:

The number 1-4 indicates the year when the patent application was accepted.

The fifth digit indicates the type of patent application,

The number 6- 12 (***7) is the application serial number, indicating the relative order of accepting patent applications.

The last decimal point is the parity bit.

The meaning of the fifth digit is as follows: 1 stands for invention patent application; 2 represents an application for a patent for utility model; 3 represents an application for a patent for design; 8 denotes the PCT invention patent application that entered the national stage in China; 9 denotes the PCT utility model patent application that entered the national stage in China.